Gastradefurphenol, a minor 9,9′-neolignan with a new carbon skeleton substituted by two p-hydroxybenzyls from an aqueous extract of “tian ma”

A minor 9,9′-neolignan with a novel carbon skeleton substituted by two p-hydroxybenzyls, named gastradefurphenol, was isolated from an aqueous extract of the Gastrodia elata rhizomes (tian ma). Solvent-dependent free rotational restriction of bonds and equilibrium of two molecular states are discussed by comparison of the NMR spectroscopic data of 1 in acetone-d6 with those in CD3OD. A plausible biosynthetic pathway of 1 is postulated to be associated with metabolic processes of l-tyrosine.